柑橘果实分泌囊发育与挥发油积累关系研究

The relationship between secretory cavity development and accumulation of essential oils in fruit of Citrus reticulata

[目的]揭示柑橘果实分泌囊发育与挥发油的积累关系，为陈皮的适时采收提供科学的形态学和植物化学依据．[方法]运用石蜡切片、半薄切片法研究了陈皮果实及其分泌囊的发育过程；利用挥发油含量测定方法对果实发育过程中挥发油含量的变化进行了分析．[结果和结论]柑橘果实从5月开始发育到笠年1月成熟，由硬变软．果皮颜色从深绿色变成金黄色或橙黄色，从不易剥离到极易剥离．分泌囊在外果皮中呈一轮排列且深浅不一，其发育过程分为4个阶段．成熟的分泌囊具有帽区和球区．后者中央有被2～5层上皮细胞包围着的大的空腔，挥发油由上皮细胞分泌出来并贮存在空腔中．随着果实的发育，挥发油的积累呈现“S”型的变化趋势．挥发油含油率在5-8月是一个平缓上升的时期，9-11月是一个快速增长期，11月中旬到达顶峰，12月初开始略微地下降．陈皮应以柑橘果实的外果皮为最佳入药部位．陈皮的最佳采收时期应为11月末到12月初，此时果实颜色为浅黄色或金黄色，分泌囊空腔平均直径最大（200μm左右），挥发油含油率最高（8.2％～8.5％）．

[Objective] The study of secretory cavity development and essential oil in the fruit of Citrus re-ticulata may provide scientific basis of morphology and phytochemistry for timely harvest of Chenpi .[Method]The developmental processes of fruit and secretory cavity were studied by paraffin section and semi-thin section method .The change of essential oil during fruit development was quantitatively ana-lyzed .[Result and conclusion] From May to January , the fruit of C.reticulata developed from hard and dark green to soft and golden yellow or orange .In the epicarp , the secretory cavities were distributed in a ring with different depths .The developmental processes of secretory cavity were divided into four sta-ges.The secretory cavity was shown to be composed of two areas：a cap area and a circular area .In the center of the latter , one big cavity was surrounded by 2-5 layers of epithelial cells .Essential oil secre-ting from the epithelial cells was stored in this cavity .With the fruit development , the accumulation of es-sential oil followed a “S” trend.The ratio of essential oil displayed a gentle rise during the period from May to August , a rapid growth from September to November , reaching a peak in the middle of Novem-ber , and a slight decline in early December .It is suggested that the medically effective fraction of Chenpi is the epicarp .The best time for harvest should be from late Novermber to early December .In this peri-od, the fruit color is light yellow or golden yellow .The average diameter of secretory cavities reaches the maximum （200 μm）, and the ratio of essential oils is also the highest （8.2%-8.5%）.